Flotation of copper-nickel sulfide ores

ABSTRACT

Flotation of sulphide minerals from their ores is achieved by a process in which two or more conditioning steps are carried out prior to a froth flotation step. The first step comprises conditioning a pulp of the ore in the presence of at least one alkaline agent selected from a group of agents which is defined in the specification which follows. The pulp is then further conditioned in the presence of a member of the xanthate family of flotation reagents and sufficient dispersing agent to effectively disperse the host rock minerals. The resulting pulp is then subjected to froth flotation. Preferably there are three separate conditioning steps, namely conditioning carried out in the presence of (1) one of the hereinafter defined alkaline agents, (2) a member of the xanthate family of flotation reagents, and (3) sodium silicate. The invention is particularly valuable for the recovery of metallic sulphides from ores containing talcy minerals or natural slimes and the invention has been applied with signal success to the flotation of copper-nickel sulphide ores containing over 40 percent weight of talcose host rock minerals.

Unite States atent Weston 1 *June 6, 1972 54] FLOTATION 0F COPPER-NICKEL FOREIGN PATENTS OR APPLICATIONS SULFIDE ORES 616,256 3/1961 Canada ..209/166 [72] Inventor. David Weston, 3 parkwood Avenuey 616,687 3/1961 Canada ..209/l66 Toronto, 7, Ontario, Canada Primary ExaminerFrank W. Lutter Notice: The portion of the term of this patent sub- Assistant E i -Rob Hal r sequent to Aug. 3, 1988, has been dis- Attorney-Smart & Biggar claimed.

[22] Filed: Nov. 3, 1969 [57] ABSTRACT Appl1 No.: 873,911

Related US. Application Data ALKALINE AGENT ACTIVATOR WETTI NG AGENT XANTHATE COLLECTOR DISPERSING AGENT FROTHER Flotation of sulphide minerals from their ores is achieved by a process in which two or more conditioning steps are carried out prior to a froth flotation step. The first step comprises conditioning a pulp of the ore in the presence of at least one alkaline agent selected from a group of agents which is defined in the specification which follows. The pulp is then further conditioned in the presence of a member of the xanthate family of flotation reagents and sufficient dispersing agent to effectively disperse the host rock minerals. The resulting pulp is then subjected to froth flotation. Preferably there are three separate conditioning steps, namely conditioning carried out in the presence of I) one of the hereinafter defined alkaline agents, (2) a member of the xanthate family of flotation reagents, and (3) sodium silicate. The invention is particularly valuable for the recovery of metallic sulphides from ores containing talcy minerals or natural slimes and the invention has been applied with signal success to the flotation of coppernickel sulphide ores containing over 40 percent weight of talcose host rock minerals.

27 Claims, 1 Drawing Figure WET GRINDING AND CONDITIONING (STEP I) FURT HER CONDlTlONlNG (STEP 2) FURTHER CON DlT|O NlNG (STEP 3) FLOTATlON ALKALINE AGENT WET GRINDING ACTIVATOR AND CONDITIONING WETTING AGENT (STEP 0 XANTHATE COLLECTOR FURTHER CONDITIONING (STEP 2) DISPERSING AGENT FURTHER CONDITIONING FROTHER (STEP 3) FLOTATION FLOTATION OF COPPER-NICKEL SULFIDE ORES This application is a continuation in part of application No. 727,268, filed May 7, 1968 now US. Pat. No. 3,596,838.

This invention relates to the flotation of sulphide minerals from their ores and is especially valuable in the case of sulphide ores containing appreciable quantities of talcy-type host rock minerals. In prior flotation procedures with appreciable amounts of such host rock minerals, large quantities of the host rock are floated with the sulphides, thereby making the operation uneconomical or resulting in low grade concentrates which are difficult or impossible to up-grade, and, in many cases, poor recoveries of the sulphide values.

In addition to the above described ores, generally referred to as talcose ores, this invention is especially useful for the recovery of sulphides from a broad field of host rock materials such as those contained in mud seams, graphite, and ores with natural slimes that interfere generally in the same manner in the flotation of sulphide ores containing talcose type minerals.

In the past, the method of treating such ores has been either to deslime the pulp before flotation resulting in major sulphide value losses, or a pre-float made ahead of the sulphide float also resulting in major sulphide losses, or where the ore is of sufficiently high grade the deleterious material is floated with the sulphides resulting in a low grade concentrate being shipped to the smelter, or alternately, cleaned many times, resulting in a medium grade concentrate with comparatively low value recoveries.

BRIEF SUMMARY OF THE INVENTION I have invented a process wherein the sulphides can be directly floated at a moderate cost from such ores, with the production of high grade concentrates and high sulphide value recoveries.

With my process there is no need to deslime prior to the sulphide flotation, or make an initial pre-float for discarding to tailings or further treatment.

As will be seen from the following, my process may involve unusual combinations of reagents together with pre-conditioning steps wherein the reagents added in each step and their concentrations are major factors in this surprisingly effective flotation procedure. It will also be seen in the following that selection of alkaline agents is most important and optimum results are only obtainable with correct combinations of agents.

My invention may be generally defined as a process for the flotation recovery of at least one sulphide mineral from an ore of the same by a process in which at least two stages of conditioning precede flotation, said process comprising conditioning a pulp of the ore in the presence of an alkaline agent preferably selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these compounds, and mixtures comprising at least one of the compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides or lime; and, in the presence of a member of the xanthate family of flotation reagents and a sufficient amount of dispersing agent to maintain the host rock minerals efiectively dispersed, further conditioning the said pulp and subjecting same to froth flotation.

The presently preferred process according to the invention includes three conditioning steps. In the first conditioning step the ore, together with activating agents or wetting agents which are to be used, is conditioned in the presence of an alkaline agent which may preferably be either an alkali metal carbonate or ammonium hydroxide, or mixtures of these compounds, or mixtures of one or both of these compounds with a hydroxide selected from the group consisting of sodium, potassium and calcium hydroxide or lime. This conditioning step is carried out for a period of time sufficient to activate the mineral or create conditions on the surface of the mineral for optimum activation and with sufficient alkaline agent to bring the pH of the resulting pulp to a point within the optimum range for flotation of the desired mineral. The pulp resulting from this first step is now subjected to a second conditioning step in the presence of a selected member of the family of xanthate flotation reagents for a time predetermined by experiment to produce maximum activation. The third conditioning step comprises conditioning the pulp resulting from the second step in the presence of dispersing agent once again in an amount and for a time predetermined by experiment to be suflicient to effectively disperse the host rock minerals. The pulp resulting from the third conditioning step is then subjected to froth flotation.

Further, as will be seen from what follows, the time of flotation required after the stages of pre-conditioning is comparatively short as compared to conventional flotation circuits, even as compared with those which are free of such deleterious material. This not only means an appreciable saving in capital cost but also a possible reduction in operating costs. Following the addition of the frother I found that the sulphides float in the rougher circuit extremely rapidly using a rougher flotation time of 7 to 12 minutes. The normal rougher flotation time in the flotation of the nickel mineral pentlandite in current conventional circuits is 45 minutes.

The data from this invention also indicates that it may be applied for additional host rock rejection to current base metal sulphide flotation plants to reduce the insol in the final concentrates now being produced from ores containing the normal host rock materials and that have theretofore not been considered troublesome. By reducing the insol in the concentrates both freight and smelter costs will be reduced.

In the detailed description which follows, I have shown that excellent results may be obtained on a copper-nickel sulphide ore using as one combination, sodium carbonate and ammonium hydroxide as the alkaline controlling reagents in the process. In the application of this process, it may well be found that on other types of ores containing different host rock constituents or other sulphides such as lead and zinc, other alkaline combinations may either be more economical or show improved results over the sodium carbonate ammonium hydroxide circuit found best for this copper nickel ore. With this copper nickel ore I have found it advantageous to use copper sulphate as an activator in the intial conditioning step, whilst with a sulphide such as galena no such activating agent is required.

When the conventional xanthate flotation method for flotation of this ore is used, the inventor was informed that the maximum grade of concentrate producible was in the range of 2-2 V2 percent nickel with recoveries of approximately 65 70 percent. With my process a concentrate grade in excess of 5 percent nickel was produced with final recoveries indicated in excess of percent.

In my process I not only found that the pre-conditioning stages were important, but also the method in which I carried out my cleaning. Again, a short conditioning stage with the addition of reagents before each cleaner gave optimum results.

BRIEF DESCRIPTION OF DRAWING A drawing is attached which is a flow sheet of the preferred embodiment of the invention.

DETAILED DESCRIPTION Referring to the drawing, in this preferred procedure which is applied to the flotation of copper and nickel sulphides from its ore, the wet grinding and first conditioning step are carried out simultaneously, the ore being fed to a wet grinding system together with a wetting agent, at least one alkaline reagent, and an activator for the nickel sulphide minerals, namely copper sulphate. When the ore has been ground to the desired fineness and the sulphides activated, the ore is taken from the grinding circuit and subjected to a second conditioning step in the presence of a selected member of the xanthate family of flotation reagents. This treatment is carried out for a period which must be predetermined by experimentation in a manner which will be described in detail later. The thus conditioned ore is subjected to a further (third) conditioning step in the presence of an amount of dispersing agent sufficient to effectively disperse and depress the host rock minerals. A conventional frother is added toward the end of the third conditionever, able to obtain satisfactory results with, in addition to the combination mentioned in Example I, sodium carbonate by itself, ammonium hydroxide by itself, sodium carbonate and ammonium hydroxide in combination with lime, sodium caring step and the resulting pulp subjected to froth flotation. 5 bonate in combination with lime alone and sodium carbonate A detailed description of the preferred procedure of the inin combination with sodium hydroxide. Because of the similar vention is set out in Example 1 which follows. The ore treated chemical properties of sodium hydroxide and potassium in Example I was a copper-nickel sulphide ore containing an hydroxide, it is apparent that potassium hydroxide could be estimated average 40 percent of talcose type minerals. The substituted for sodium hydroxide in the combinations above sample contained 0.52 percent nickel in the form of pentwhere sodium hydroxide gave beneficial results. [have set out landite and 0.25 percent copper in the form of chalcopyrite. below in tabular form the results of a series of tests using vari- The ore was ground in a laboratory rod mill at 60 percent ous alkaline reagents, the conditions in each case being exsolids to afineness of about 95 percent minus 200 mesh in the actly the same as described in Example 1 except for the inpresence of the equivalents of 7.5 pounds per ton of ore of dicated changes in the alkaline reagent(s) employed. sodium carbonate, 0.62 pounds per ton of ore of ammonium The test numbers are shown in the first column of this table hydroxide, 0.45 pounds per ton of ore of activator (copper and test No. 204 is the test which gave the results fully set out sulphate) and 0.075 pounds per ton of ore of a wetting agent above in Example I. which was a trimethyl nonyl ether of polyethylene glycol. The It is immediately apparent from a study of Table I that the grinding time was 40 minutes during which period the first results obtained with calcium hydroxide alone, sodium conditioning step was completed. The resulting pulp was then hydroxide alone or a combination of these two components TABLE I [Table showing elloct of use of different alkaline reagents] Alkalis used, lbs/ton Rougher tailings, percent Test, pH No. Step 3 NELZCO3 NHlOII Ca(OH)z NaOH Wt. Ni Cu 0. 8 7.5 0. 62 0.0 0. 0 75. 7 0. 007 0.018 0.5 0. 0 0. 62 5.0 0. 0 73.1 0.107 0.010 0. s 0. 0 0.02 7. 5 0. 0 0s. 7 0.110 0.010 0. 7 0. 0 0.0 0. 0. 02 72. 0 0.123 0.010 0. 85 3. 75 0. 02 .s. 75 0. 0 00. 0 0. 000 0. 010 0. 75 7.5 0.0 0. 0 0. 02 74. 0 0.107 0.010 0. 7 s. 1 0. 0 0. 0 0. 0 74. 5 0.101 0. 010 I. as 0. 0 0. 0 0. 0 3. 0 75. 0 0.113 0. 010 0.4 0. 0 1.25 0. 0 0.0 73. x 0.104 0.018 0. 0. 0 0. 0 0. 25 0.0 07. 2 0. 110 0.010

subjected to a second conditioning step for a period of 20 gave inferior metallurgical results. Throughout this table the minutes with the addition of 0.125 pounds per ton of potassiillustrations shown represent the best metallurgy that was atum amyl xanthate. The pulp resulting from the second conditained in optimizing such reagent or reagent balances. tioning step was subjected to a third conditioning step for a Reference will now be made to the manner in which one period of 10 minutes in the presence of 35 pounds sodium silmay predetermine the optimum conditioning periods. To aricate per ton of ore. At the end of the second step the sulrive at the optimum period for conditioning during step 1, one phides showed heavy floculation at the surfa e of th p lp. runs a series of tests, the first being taken immediately at the Following the addition of sodium silicate in the third step, the end of grinding and further tests at intervals of a few minutes host rock was heavily dispersed while the sulphide fiocs only u to an hour of conditioning subsequent to completion of partially broke up. At the end of approximately 1 minute folgrinding. If no economic improvement is shown by additional lowing the addition of sodium silicate the sulphide flocs conditioning after grinding, one would, of course, immediately strongly reformed while the host rock minerals remaine proceed with conditioning step 2 but if improvement is realheavily dispersed. The pH of the pulp at the n f the third ized with further conditioning, the cut-off point in time will be conditioning ste was 9.8. During the last 2 minutes of this a factor of the increased mineral recovery vs. the cost of conditioning stage, frother was added which was two drops of further conditioning. This may be illustrated by comparing the pine oil. The resulting pulp was then subj to froth fiotaresults which were obtained with tests 150 and 162 which will tion for a period of 12 minutes during which 0.05 pounds per now be described as Examples ll and Ill respectively. ton of xanthate was added and two additional drops of pine oil. The pulp temperature was 36 C. EXAMPLE I] The rougher tailings amounted to 75.6 percent by weight Test 150 and were remarkably low in nickel content. The nickel analyh Wetting agent, sodium carbonate, ammonium h dro sis was 0.097 percent while the copper analysis was 0.018 peride and copper sulphate were added to the grinding circuit at cent. So far as I am aware, it has never in the past been possithe rates of 0.075, 7.5, 0.62 and 0.45 lbs. per ton respectively. ble to obtain results of this order in the case of an ore having a Step I took place simultaneously with the grinding and step 2 talcose content of this magnitude. was a 7 minute conditioning cycle with 0.125 lbs. per ton of While in the preferred process described in detail above all potassium amyl xanthate (26) added. In step 3, 35 lbs. per ton of the first conditioning step is completed during wet grinding of sodium silicate was added and the conditioning time was 10 it should be appreciated that the first step might be carried out minutes. The frother was pine oil and during rougher flotation partially during wet grinding, with the remainder of this first 0.05 lbs. per ton of Z6 (potassium amyl xanthate) was added. conditioning step being conducted after the grinding has been The rougher tailings were 80.1 percent by weight and completed. F Urthermore, in certain cases it may be desirable analyzed 0.101% nickel. to carry out the entire first conditioning step after either wet EXAMPLE m or dry grinding.

As indicated above, other alkaline reagents may be em- Test 162 ployed but experiments I made with the conventional alkaline This test is a near duplicate of Test with the exception reagent used in the flotation of copper and nickel sulphides, that step 1 included a 45 minute conditioning period following namely lime, gave poor recoveries and had a tendency to floa the grinding stage. All other conditions were the same with the an appreciable percentage of the host rock. The use of sodium exception that slightly less wetting agent was used, namely hydroxide by itself also gave unsatisfactory results. I was, how- 7 0.0625 lbs. per ton.

The rougher tailings were 79.8 percent by weight analyzing 0.097 percent nickel.

In comparing this test to Test 150 the inclusion of additional conditioning following grinding and before the xanthate conditioning indicates a slightly higher recovery but may not be economically justified.

The optimum conditioning time for the second conditioning step is illustrated by Table 11 below which describes five tests carried out under the same conditions except for the length of time devoted to conditioning step 2. As with all the tests reported throughout this specification, the work was done on three samples of the same copper nickel ore basically varying in talc content from an estimated minimum of 25 percent to a maximum of 50 percent. The series of tests making up each individual series were, of course, conducted upon the same sample of ore.

TABLE II Rougher tailings,

The major break in the tailings loss takes place between 5 and minutes conditioning time and shows a further small which is approximately percent higher than the lower limit tested.

EXAMPLE IV In these two comparative tests, all reagents and conditioning periods were the same with the exception that in test 120, 37 :6 pounds per ton of sodium silicate was used as against pounds of sodium silicate per ton of ore in test 123. It was found that in test 123 the sodium silicate concentration had dropped below the lower effective concentration of the dispersant for optimum metallurgical results. In test 120, the percentage weight of the ore rejected in the tailings was 78.1, analyzing 0.130 percent nickel, as against the lower tailings rejection in test 123, that is 74.7 percent by weight analyzing 0.144 percent nickel. It is obvious that the percentage of material floating suffered and that there was a higher nickel loss in the tailings when the sodium silicate concentration is lower than that required to effectively disperse and depress the host rock minerals.

While I generally prefer to add all the dispersant during the third conditioning step, I have found it possible to add a minor part in step 1 and the major part in step 3. Results obtained from adding a portion of the dispersant during this first step are shown in Table IV.

TABLE IV Rougher tailings,

Rougher tailings,

Conditioning time, mins. percent Test No. Step 1 Step 2 Step 3 Wt. Ni Cu 210 i Grinding cycle 20 2. 5 74. 6 0, 096 0.018 only 20 5. 0 75. (i O. 0517 0. 017 throughout 20 10.0 75. 6 O. 0H7 0.018 tests .20 20. 0 75. 7 0. 103 O. 018

It will be noted that the tailings loss increases between 10 and 20 minutes conditioning with no noteworthy differences in metallurgy between 2 1% and 10 minutes. It may be seen from this table that the third conditioning step for optimum results should not be carried on for more than 10 minutes and the preferred period is some 2 k to 5 minutes. It will also be noted that at 20 minutes metallurgy sufi'ers. In this cycle it is therefore important not to exceed the selected time period by an appreciable time.

The amount of sodium silicate which should be present during the third conditioning step must also, in the case of each ore, be pre-determined by experiments. On an ore of this type with high talcose content using conventional flotation means well-known to the art, the mass of the ore tends to float producing a very low grade concentrate. To obtain the optimum amount of sodium silicate required to substantially disperse and depress the host rock minerals, I keep increasing the amount of sodium silicate until a comparatively cleari differential sulphide float is obtained. I then continue with a slight excess over this amount and then conduct a series of controlled tests using lesser amounts until the host rock again begins to interfere with the float and the amount of sulphide In comparing the results of these tests to 204 wherein all of the dispersant was added to step 3, as against approximately 30 percent to the grinding circuit with 70 percent to step 3 (Test 209), the results, although slightly poorer, may be considered a stand-ofl.

With 50 percent (Test 217) of the dispersant added to the grinding circuit and 50 percent to step 3, there is a noticeable increase in tailings loss of nickel. From an operational point of view where it may be desirable to circulate part of the recovered solution from the flotation circuit tailings to the grinding circuit, and wherein there will be a number of the reagents including sodium silicate partially recovered, this characteristic of the circuit in being able to tolerate somewhat in excess of 30 percent of the total sodium silicate required without undue nickel loss can be important economically in reduction in the overall reagent cost as shown in this open circuit work.

The effect of reversing the times of addition of the sodium silicate dispersant and the xanthate collector is illustrated in Table V in which the sodium silicate is added during step 2, and the xanthate in step 3.

TABLE V Conditioning time, mins.

Step 1 Step 3 Rougher tailings, percent Wt. Cu

Step 2 Ni considerable improvement over any prior knowledge in the art 7 in the treatment of such talcy-natured ores.

EXAMPLES v1 This example, which includes a description of rougher concentrate cleaning, was carried out on an ore sample taken from the same ore body as the samples used in the preceding examples. This sample, however, had a higher percentage of talc, probably exceeding 50 percent, and was the most refractory to flotation treatment.

Reagents added during grinding 0.075 lbs. per ton-wetting agent 0.45 lbs. per ton-CuSQ,

0.62 lbs. per ton-Nl-LOH 8.75 lbs. per ton-Na CO Step 1 the grinding time plus 15 minutes of further condi- 15 tioning. Step 2 0.125 lbs. per ton potassium amyl xanthate,

minutes conditioning Step 3 40 lbs. per ton Na SiO minutes conditioning, 2 drops pine oil last two minutes of conditioning Float 12 minutes with addition of 0.05 lbs. per ton potassium amyl xanthate and 1 drop of pine oil. The rougher concentrate was conditioned for 5 minutes with the following reagents added:

Wetting agent-0.0 l 2 lbs. per ton Potassium amyl xanthate-0.025 lbs. per ton N1-I.,O1-10.25 lbs. per ton Na,SiO -l .5 lbs. per ton The number 1 cleaner concentrate was conditioned for 5 minutes with the following reagents added:

NI-1 Ol-l0.25 lbs. per ton Na SiO -1.5 lbs. per ton 10 cent minus 200 mesh.

The following table shows the circuit used in all tests:

Stage I 30 min.: Grinding cycleAdded alkali agent and copper sulphate. 10 min.: Conditioning in Fagergren cell. No reagents added.

Stage II min.: Added collector-potassium amyl xanthate State 111 3 min.: Added dispersant and frother which was pine oil.

Rougher Float 5 min.

20 Stage IV To rougher concentrate in Fagergren cell Conditioned for 5 min. with added dispersant. First Cleaner Float-To clean-up.

(Note-With some ores Stages I1 and Ill may be combined with dispersant and collector added together, and f rother at end 1.

The following results show the rougher tailings rejection only for comparative reasons, although in my process 1 have found it most desirable to use Stage IV wherein to obtain the lowest possible insol in the final concentrate, the rougher concentrate should be conditioned from 1 to 3 minutes with the further additions of dispersant.

TABLE VII Reagents, lbs/ton Roughcr tailings, percent Tetrasodium Lignm Test Float. pyro-phossu1ph0- P11 Wt. Ni Cu NazCoi C1180; Z6 NazSiOz photo unto 1. 0 s0. 0 0. 036 0.012 7. 5 0. 10. 15 80. 2 o. 0311 o. 012 11. 25 0.35 10. 15 s0. s1 0. 03s 0. 012 11. 25 0. 35 10. 15 711.8 0. 03s 0. 012 11. 25 0. 35 10. 35 711. s 0. 0311 0. 010 13. 75 0. 35

The results obtained are Shown belowin Table v It will be noted that the two families of dispersants, the phosphates and hgnin compounds, gave excellent dispersion TABLE V1 with much less quantity than the silicate, and had no detrimen- Anal sis 7 Ni tal effect on the nickel or copper metallurgy.

0 o Produc Weight Dish It should be further noted that with my c1rcu1t and efficiently using the pre-conditioning chemically controlled stages excellent rougher flotation recovery of the nickel and No. 2 Cleaner Concentrate 6.2 5.63 67.1 2 cleaner Tamngs 28 0'71 39 copper wasachieved 1n a flotation period of only 5 mmutes. No. 1 Cleaner Tailings 31.0 0.27 16.1 In the P110r aPPIICaHOH Of y Process 10 high talc bearing Rougher Tailings 60.0 0.1 12 12.9 nickel-copper ores I had found that lime or calcium hydroxide Total: 100.0 100.0

Rouglur killings, percent alone as the alkaline control agent would not give as good results as other alkalis, or combination of alkalis.

The following series of tests were conducted on the same ore referred to above to determine the relative merits of calcium hydroxide and sodium carbonate in my circuit, wherein only a medium slime factor of an ore was present. The same circuit was used as described above.

TABLE VIII Hangouts, lbs/ton Wt. Ni C11 Ni'l2C-()f( (11((110 (1180 Z6 NagSiOi 80. 0 (l. 036 0. 35 0.15 l 0. 5 80. 0 0. 038 O. 35 0. 15 0. 05 82. i 0. 005 0. 35 0. 15 0. 5 81. 1 0. 059 0. 35 O. 15 0. 81. 3 0. 059 0.35 0. 15 0. 625 82. 0 0. 050 O. 35 0. 15 O. 5

1 Lignin.

At a grade of approximately 5 percent nickel, analysis of the concentrate showed an insol content of approximately 13 percent which is considered excellent in the case of such ores.

The following series of tests were carried out to determine if It will be noted that the soda ash circuit showed improved recoveries in both nickel and copper over the lime circuit,

75 although the former required much higher quantities of alkali,

and as soda ash is normally much more expensive than lime,

under some conditions of operation it may be better economics to use lime rather than soda ash on such a type of nickel copper ore.

The results with the lime circuit, in comparison to current conventional milling is quite outstanding.

What I claim as my invention is:

1. A process for the flotation recovery of copper and nickel sulphide minerals from ore containing both such minerals by a process in which at least two conditioning steps precede flotation, said process comprising: conditioning a pulp of the ore in the presence of an alkaline agent to produce a conditioned alkaline pulp; then, in at least one further conditioning step, further conditioning said pulp in the presence of a member of the xanthate family of flotation reagents and a predetermined amount of a dispersing agent to activate said minerals and depress the host rock materials; then subjecting the thus conditioned pulp to a rougher flotation to produce a concentrate relatively rich in said minerals and relatively poor in host rock material; repulping said concentrate with the addition of further dispersing agent to further depress the host rock materials; and then subjecting the thus further conditioned pulp to a first cleaner flotation to produce a concentrate relatively richer in said mineral and poorer in host rock material than said rougher concentrate.

2. A process as defined in claim 1 wherein the dispersing agent is sodium silicate.

3. A process as defined in claim 1 wherein the dispersing agent is a phosphate.

4. A process as defined in claim 1 wherein the dispersing agent is a lignin compound.

5. A process as defined in claim 1 wherein the conditioning in the presence of an alkaline agent takes place at least partially during wet comminution of the ore.

6. A process as defined in claim 1 wherein the ore is a talcose ore that contains a nickel sulfide mineral and the alkaline agent is selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these compounds, and mixtures comprising at least one of the compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides or lime.

7. A process as defined in claim 6 wherein the dispersing agent is sodium silicate.

8. A process as defined in claim 6 wherein the dispersing agent is a phosphate.

9. A process for the flotation recovery of copper and nickel sulphide minerals from ore containing both such minerals by a process in which at least two conditioning steps precede flotation, said processing consisting essentially of (a) conditioning a pulp of the ore in the presence of at least one alkaline agent selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures ofthese compounds, and mixtures comprising at least one of the compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides; and then, (b) in the presence of a member of the xanthate family of flotation reagents and a sufficient amount of dispersing agent to maintain the host rock minerals effectively dispersed, further conditioning the said pulp and subjecting same to froth flotation.

10. A process as defined in claim 9, in which the first conditioning step is at least partially carried out during one or more wet grinding stages.

11. A process as defined in claim 9, in which the entire first conditioning step is carried out subsequently to one or more wet grinding stages.

12. A process as defined in claim 9, in which the alkaline agent is sodium carbonate.

13. A process as defined in claim 9, in which the alkaline agent is ammonium hydroxide.

14. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and ammonium hydroxide.

15. A process as defined in claim 9, in which the alkaline agents are sodium carbonate, ammonium hydroxide and calciurn hydroxide or lime.

16. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and sodium hydroxide.

17. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and calcium hydroxide.

18. A process as defined in claim 9, in which copper sulphate is added as an activating agent during said first conditioning step.

19. A process as defined in claim 9, in which a trimethyl nonyl ether of polyethylene glycol is added as a wetting agent during said first conditioning step.

20. A process as defined in claim 9, in which the xanthate reagent employed is sodium amyl xanthate.

21. A process as defined in claim 9, in which the xanthate reagent employed is potassium amyl xanthate.

22. A process for the flotation recovery of copper and nickel sulphide minerals from ores containing both such minerals by a process in which at least two conditioning steps precede flotation, said process consisting essentially of (a) a first conditioning step wherein the ore, together with such activating agents and wetting a cuts as are to be used, is conditioned in the presence of at east one alkaline agent selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these two compounds, and mixtures comprising at least one of these compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides, in an amount calculated to bring the pH of the resulting pulp up to a point within the optimum range of flotation of the desired mineral, for a period of time sufficient to activate said mineral; then (b) a second conditioning step wherein the pulp resulting from the first step is conditioned in the presence of a selected member of the family of xanthate flotation reagents for a period of time determined by experiment to produce maximum activation of said minerals; then (c) a third conditioning step wherein the pulp resulting from the second step is conditioned in the presence of a dispersing agent in an amount and for a time, predetermined by experiment, to be sufiicient to effectively disperse the host rock minerals; and then ((1) subjecting the resulting pulp to froth flotation.

23. A process as defined in claim 22, in which the second conditioning step is carried out for a period of from 10 to about 30 minutes.

24. A process as defined in claim 22, in which the third conditioning step is carried out for a period of less than 10 minutes.

25. A process as defined in claim 22, in which the second conditioning step is carried out for a period of from about 10 to about 30 minutes, and in which the third conditioning step is carried out for a period of less than 10 minutes.

26. A process as defined in claim 22, in which the dispersing agent is added as dispersant during both the first and third conditioning steps, the amount added in the first step being less than that added in the third step.

27. A process according to claim 22, wherein the order of the second and third conditioning steps is reversed and the total time of the third conditioning step is at least 5 minutes. 

2. A process as defined in claim 1 wherein the dispersing agent is sodium silicate.
 3. A process as defined in claim 1 wherein the dispersing agent is a phosphate.
 4. A process as defined in claim 1 wherein the dispersing agent is a lignin compound.
 5. A process as defined in claim 1 wherein the conditioning in the presence of an alkaline agent takes place at least partially during wet comminution of the ore.
 6. A process as defined in claim 1 wherein the ore is a talcose ore that contains a nickel sulfide mineral and the alkaline agent is selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these compounds, and mixtures comprising at least one of the compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides or lime.
 7. A process as defined in claim 6 wherein the dispersing agent is sodium silicate.
 8. A process as defined in claim 6 wherein the dispersing agent is a phosphate.
 9. A process for the flotation recovery of copper and nickel sulphide minerals from ore containing both such minerals by a process in which at least two conditioning steps precede flotation, said processing consisting essentially of (a) conditioning a pulp of the ore in the presence of at least one alkaline agent selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these compounds, and mixtures comprising at least one of the compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides; and then, (b) in the presence of a member of the xanthate family of flotation reagents and a sufficient amount of dispersing agent to maintain the host rock minerals effectively dispersed, further conditioning the said pulp and subjecting same to froth flotation.
 10. A process as defined in claim 9, in which the first conditioning step is at least partially carried out during one or more wet grinding stages.
 11. A process as defined in claim 9, in which the entire first conditioning step is carRied out subsequently to one or more wet grinding stages.
 12. A process as defined in claim 9, in which the alkaline agent is sodium carbonate.
 13. A process as defined in claim 9, in which the alkaline agent is ammonium hydroxide.
 14. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and ammonium hydroxide.
 15. A process as defined in claim 9, in which the alkaline agents are sodium carbonate, ammonium hydroxide and calcium hydroxide or lime.
 16. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and sodium hydroxide.
 17. A process as defined in claim 9, in which the alkaline agents are sodium carbonate and calcium hydroxide.
 18. A process as defined in claim 9, in which copper sulphate is added as an activating agent during said first conditioning step.
 19. A process as defined in claim 9, in which a trimethyl nonyl ether of polyethylene glycol is added as a wetting agent during said first conditioning step.
 20. A process as defined in claim 9, in which the xanthate reagent employed is sodium amyl xanthate.
 21. A process as defined in claim 9, in which the xanthate reagent employed is potassium amyl xanthate.
 22. A process for the flotation recovery of copper and nickel sulphide minerals from ores containing both such minerals by a process in which at least two conditioning steps precede flotation, said process consisting essentially of (a) a first conditioning step wherein the ore, together with such activating agents and wetting agents as are to be used, is conditioned in the presence of at least one alkaline agent selected from the group consisting of alkali metal carbonates, ammonium hydroxide, mixtures of these two compounds, and mixtures comprising at least one of these compounds and at least one hydroxide selected from the group consisting of sodium, potassium and calcium hydroxides, in an amount calculated to bring the pH of the resulting pulp up to a point within the optimum range of flotation of the desired mineral, for a period of time sufficient to activate said mineral; then (b) a second conditioning step wherein the pulp resulting from the first step is conditioned in the presence of a selected member of the family of xanthate flotation reagents for a period of time determined by experiment to produce maximum activation of said minerals; then (c) a third conditioning step wherein the pulp resulting from the second step is conditioned in the presence of a dispersing agent in an amount and for a time, predetermined by experiment, to be sufficient to effectively disperse the host rock minerals; and then (d) subjecting the resulting pulp to froth flotation.
 23. A process as defined in claim 22, in which the second conditioning step is carried out for a period of from 10 to about 30 minutes.
 24. A process as defined in claim 22, in which the third conditioning step is carried out for a period of less than 10 minutes.
 25. A process as defined in claim 22, in which the second conditioning step is carried out for a period of from about 10 to about 30 minutes, and in which the third conditioning step is carried out for a period of less than 10 minutes.
 26. A process as defined in claim 22, in which the dispersing agent is added as dispersant during both the first and third conditioning steps, the amount added in the first step being less than that added in the third step.
 27. A process according to claim 22, wherein the order of the second and third conditioning steps is reversed and the total time of the third conditioning step is at least 5 minutes. 